Various types of safety latches, locks, door restraint mechanisms and fastening devices have been devised for preventing the opening of a door and the unauthorized intrusions of persons. Many such devices, such as dead bolt locks, can be picked, wrenched, or pried from the outside by intruders and thus do not offer the individual t he desired security.
It is known in the prior art to provide a means for engaging the latch bolt hole and the hole in the striker plate, and to secure the face of the door to the latch bolt hole independently of the normal door lock. U.S. Pat. No. 4,155,578 (Rolland) shows a portable latch which has a cable which engages the knob, and where a cable is secured to the jam insert mechanism by means of a V-notch. In the prior art, it is also known to compensate for torque on the safety latch by engaging the door knob as shown in U.S. Pat. Nos. 4,334,705 (Rumph), 2,532,586 (Wickwire), 827,624 (Foster) and 4,575,140 (Dargis).
U.S. Pat. No. 913.223 (Minderlein) discloses a door latch lock
has a male thread and nut located on the portion which extends in and engages the bolt hole in the jam, and which provides for adjustments of the mechanism to tighten it against the door.
U.S. Pat. No. 4,155,578 (Rolland) shows a safety latch for inward swinging door which includes a fixable member to attach the door handle to the strap which engages the latch bolt hole in the door frame. The means for engaging the inward face (25) does not secure the flexible member when wrapped around the door knob.